Heretofore, bed rollers have taken various forms from an ordinary type furniture caster to massive oversize rollers intended to take the heavier loads ordinarily imposed by a bed, especially the larger size beds so widely used today. Some prior casters of the larger type, such as U.S. Pat. No. 1,432,966, involved the use string guards to avoid picking strings, or threads, as from a bedroom rug, or carpet. Certain prior casters especially designed for use under beds, such as in U.S. Pat. No. 2,964,778, utilized exceedingly wide rollers for the necessary support and to minimize excessive wear on floor coverings caused by frequent moving of the bed.
Two wheel casters are utilized by patents such s Ger. No. 25 13 565 and U.S. Pat. Nos. 3,822,437 and 3,805,320 as well as 3,648,325 and 4,077,088. A six wheel dolly caster was disclosed U.S. Pat. No. 2,713,179 but this device was more in the nature of a truck designed to cope with excessively large and very heavy loads, such as safes, machinery, crates and the like.
This latter arrangement utilized three wheels forward and three wheels to the rear with the wheels tracking the same paths and mounted by means of longitudinal supporting plates at opposite sides of all of the wheels and mounted on upper horizontal hinge pin extending through depending lugs on a rectangular body plate which has relative movement with respect to a top steering plate with means for slight angling movements so that a heavy load may be sterred to some extent.
U.S. Pat. No. 3,140,506 discloses a roller arrangement having peripheral surfaces designed to avoid the forming of depressed areas in the pile of a carpet, or rug upon which the caster supports an article of furniture and involves the use of multiple discs and radially extending fingers between the discs with both the discs and the fingers separating the pile fibers to pass therebetween without matting them down.